


A Matter of Mutation

by Queen_B



Series: OT4 [6]
Category: Teenage Mutant Ninja Turtles - All Media Types
Genre: Anal Sex, Beware, First Time, M/M, Turtlecest, doesn't make sense science-wise
Language: English
Status: Completed
Published: 2018-02-05
Updated: 2018-04-10
Packaged: 2019-03-14 07:24:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 6,858
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13585146
Author URL: https://archiveofourown.org/users/Queen_B/pseuds/Queen_B
Summary: A look back to when our favorite turtles got together and experimented in the bedroom.Heavy turtlecest.





	1. Chapter 1

**Author's Note:**

> Please note that I have absolutely no idea about turtles in nature and my (Donnie's) explanation doesn't make any sense at all, but for the sake of the fic bear with me, alright? 
> 
> Btw, if there's something you'd like me to write in this universe, don't be afraid to ask :)
> 
> Enjoy!

* * *

 

 

“Ngh, stop. I told you this wouldn't work.”

 

Leo glared up at his immediate younger brother from his place between his legs.

 

“It would work if you'd just allow yourself to relax.” Raph rolled his eyes and sighed, turning to look at Donatello, who sat next to him, looking thoughtful.

 

“I am relaxed! It just feels... weird.”

 

“It will feel better!” Leo sighed and sat up more, withdrawing his lubed finger from prodding Raph's entrance. “You promised you'd let me top.” His frown was more of a pout, and if Donnie wasn't so deep in thought he would've thought it looked funny.

Raphael propped himself up on his elbows.

 

“Hey, I'm here, ain't I?! I can't help it, it just feels uncomfortable.” The emerald turtle crossed his arms and glared at the ceiling when his head hit the pillow again.

 

“You're doing it on purpose so we'd give up.” Leo accused and crossed his arms too, mouth tugged down at the corners.

 

It's been three weeks since they figured out their feelings for each other. It had ended in a rather hot make-out session. Leo, at that time still struggling with 'PDA' and Mikey, flushed for some reason, had withdrawn when Don and Raph got more intimate.

 

They had told their Sensei right away, in hopes of being accepted. It was a shock for the elderly rat, but after a long meditation session he allowed them to proceed. It would be cruel to take away their only chance of experiencing such love.

However, they decided to take things slow. They kept their own bedrooms, though Leo and Mikey shared a bed quite often to cuddle. As for their brothers... they had no problems getting physical that fast.

 

It wasn't long before Leo's libido got the better of him and he joined his two brothers in their bedtime activities. Michelangelo still didn't feel quite comfortable enough to get that intimate, so he kept to himself when his older brothers were busy. He soaked up every bit of affection he got, he loved to be cuddled and kissed, and eagerly responded to touches, but as soon as things got heated, he would freeze up and excuse himself.

His brothers found that weird, but they vowed they wouldn't push him. He would come around eventually.

 

So for the time-being they kept to threesomes and one-on-ones, where somehow Raph always ended up on top. It was fine with Donatello, and Leo gave in the first time too. However, it irked him that it seemed to become a pattern. A pattern he wanted to break soon.

The olive turtle expected an argument when their leader had asked Raph to submit to him. Sure, he could've just tried to dominate him during intercourse but somehow... every time things heated up in the bedroom, Leo's resolve crumbled and he ended up bottoming. So he figured if he asked beforehand, things wouldn't get out of hand, so to say.

 

Anyways, Raph had agreed quite easily after a bit of coaxing. Apparently he loved and respected them enough to not ruin their relationship over something so stupid as their roles in bed.

 

“Leo, I'm layin' here with you fingering my fuckin' asshole. I'm _trying!”_

 

And the blue-banded turtle had to admit it was true. They've been on it for almost two hours now. Making out, blowjobs, everything to help Raph relax and it went awesome for a while. Until the aroused scent hit them full force and Leo was on the verge of just submitting again. About that time they started the prepping, and well... that wasn't going so awesome.

 

The leader sighed in defeat and sat back against the foot of the bed, arms still crossed.

 

“I don't get it. There's no way you're not enjoying this at all. Of course it's uncomfortable at the beginning but even I was able to relax after a while.” Raph sat up too and leaned against the headboard, facing his brothers, while Donnie finally voiced his string of thoughts.

 

“Well... I'm beginning to think that this has to do with our mutation...” the older ones blinked at him. “I mean, like... like Leo and Mikey are warm-blooded and Raph and I cold-blooded. It could be that Raph got more turtle DNA. Dominant turtle DNA.” He thought for a moment before clarifying. “It's quite uncommon, but if there's only male turtles in a group some of them become more dominant. Their penises become slightly larger and they give off a scent that gets the other turtles to submit. It seems like Raph is such an alpha turtle. They rarely enjoy being penetrated.”

 

While Donnie talked, Raph's expression turned very pleased, while Leo's frown deepened. The olive turtle smiled a little at the display. Of course the leader wouldn't like that.

 

“There. Not my fault. Can we continue now?” Seeing Leonardo still seemed a little peeved Donnie smirked. He knew just the way to get him in the mood again.

He leaned forward on his hands and knees until he was facing Leo's cock. It had deflated a little during their break, but now that Donnie's hot breath hit it, it stirred again. The olive turtle smirked again and began licking at the stiffening flesh, churring when Leo did. He started to suck on the tip, feeling Raph move beside him and pull Leo into a bruising kiss.

 

The bulky turtle moved to kneel behind his leader, pressing his plastron against Leo's shell. He nipped at the forest green neck while fondling the wiggling tail. With a dirty smirk he rubbed his own cock and Leo's tail together, shuddering at the feeling. As soon as he heard Leo moan, Raph grabbed the lube from where the eldest had discarded it before and coated his fingers with it.

 

He traced the puckered entrance, gentle despite his nature, before easing a finger inside. Leo churred and bowed a little so he could reach Donnie's tail in turn, massaging it between his fingers.

 

“Donnie? Are you in here?” Mikey's muffled voice startled them before the door to the genius' room was pushed open. The turtles on the bed looked at him from their respective positions, while Mikey blinked. A blush was slowly creeping up on his face at the sight. Seconds ticked by, none of them moved. Raph was the first to react and pumped his finger further into his older brother. Leo, in turn, continued to fondle Donnie's tail, encouraging him to pick up the sucking again.

There was a sharp intake of breath from the door, accompanied by a churr that set off more churrs from the mating brothers. An aroused scent, a different one, wafted over them, sending shivers through all of their bodies, along with a strange need.

 

“I'm sorry!” Mikey squeaked and quickly shut the door. The scent lingered for a second before it vanished.

 

Dark blue, green and mahagony eyes shared a look. They had hoped their baby brother would join in. The scent must've come from him, and it had them craving for more. They had agreed not to push him, but it was getting harder to resist...

 

 

 

~*LINEBREAK*~

 

 

 

Mikey had locked himself in his room for the rest of the night. After their coupling the brothers had tried to talk to him, but the youngster had pretended not to hear them. So they decided to leave it for now.

 

The next morning Mikey was standing in the kitchen, humming as he was working on a huge stack of pancakes.

 

“Morning!” he greeted his brothers cheerfully when they piled in. “Father's visiting Mr. Murakami.” he enlightened them after placing the stack of pancakes in the middle of the set table.

 

For the time-being they decided to give him a sense of security and greeted him with a smile. Donnie placed a small kiss on his cheek before he sat down. The small nervous vibe coming from Mikey eased into relief immediately and they all enjoyed an awesome breakfast together.

 

“So about yesterday...” Leo started while he dried the dishes half an hour later. Mikey sighed. So that's why his brothers all stayed in the kitchen to help with the cleaning.

 

“Um yeah. I'm sorry I interrupted.” There was a faint rosy color on his cheeks, prompting Donnie to cup Mikey's chin and steal a kiss.

 

“Don't be sorry. You didn't interrupt... we... we were actually hoping you would join us.” The blush darkened and his shoulders hunched as he looked into the sink's water, not quite able to meet their eyes. Donnie grabbed his wet hands and pulled him towards him, tilting his chin up again to meet those lovely blue eyes.

 

“Sweetheart, it's been weeks. We don't have to go all the way if you don't feel ready yet, but you know... we could at least fool around a little... to help you get used to the more intimate touches...” Raph found the blush on Donnie's face adorable as he talked. The purple-banded turtle would've glared at him if he had time to. At the moment he was very busy trying to reassure their youngest mate, thank you very much.

 

“I... I want to. I really do...” He couldn't quite meet his brothers' gazes. “B-But... I'm scared.”

 

“Oh baby...” Donnie pulled Mikey out of the kitchen into the living room, sending a look at their older brothers to stay put. He sat down on the couch and placed his baby brother on his lap. It was way more comfortable here and he really hoped he could take away his fears now. They've always been best friends after all. Maybe Mikey felt less scared when it was just the two of them for now.

 

“What are you scared of?” He smiled gently when Mikey shrugged and fiddled with his fingers.

 

“That you'll be disgusted.” It was only a silent murmur, but Don heard anyways. Mahagony eyes widened.

 

“Honey, we could never be disgusted by you! We love you, and every part of you. And if you'd let us we could show you...”

 

“It's... it's not that...” Donnie's heart bled a little when he saw tears pooling in those lovely baby blues. “I...” His gaze dropped again, sniffing lightly, prompting Donnie to engulf him in a tight embrace. He gently kissed the sea-green head, cradling him.

 

“You're scaring me, sweetheart... What's wrong?”

 

“I'm broken down there!” Mikey wailed, face buried in Donnie's neck and tears falling freely down his cheeks. The genius blinked, more confused than anything, and did his best to comfort his brother. He shook his head at Leo and Raph's worried faces at the doorway, indicating he'd manage on his own.

 

“Broken?” he dared to ask when Mikey calmed down enough. The smaller turtle snuggled closer to his big brother and stayed quiet. Donnie frowned worriedly and swiftly stood up with Mikey cradled in his arms bridal style. Mikey blinked in surprise and clung to Don's neck.

 

In the lab the olive turtle locked the door behind them and set Mikey down on the exam table. Gently he held Mikey's cheek and smiled encouragingly.

 

“Tell me why you think you're broken. I promise, whatever it is, I will try to fix it.” Mikey seemed a little calmer in the safety of Donnie's lab.

 

“P-Promise you won't abandon m-me?” The quiet unsure voice broke Donatello's heart. Using both hands now to hold Mikey's face he locked eyes with him.

 

“I promise that we will never, for nothing in the world, abandon you.” Mikey's eyes were still wet, but he managed a small honest smile.

 

“Okay...” he took a deep breath, reassured by Donnie's warm hands rubbing his arms.

 

“When... when I first got aroused... before we got together, I tried, you know, jerking off. Like those guys on the internet.” he was blushing a little, but soldiered on after Donnie nodded. They've all done it at some point, so there was nothing to be ashamed of.

 

“And... it just didn't work. I mean, I couldn't finish.” There was a frown on the genius' face now. “And I really tried it long enough and I don't know, it felt good. But it wasn't... _enough_.” Thinking he was done, Donnie opened his mouth, but Mikey beat him to it. “And... I think... I don't know... I got wet somehow.”

 

“Wet?” Donnie blinked in confusion, gaze dropping to where Mikey's pouch was. The nunchuck-wielder nodded, face red.

 

“Like... my... my ass was leaking.” At Donnie's confused expression he averted his gaze again. “S-Sorry. I should've kept my mouth shut...”

 

“No, baby, no!” Don quickly stopped him, pulling him close again. “It's good you told me. And I think I know what's going on with you. I just need to check something.”

 

“I'm not broken?”

 

“No, sweetheart, you aren't. To... to confirm my theory we'll need to get you aroused. Is that okay?” Mikey gulped and blushed, but nodded.

“Don't worry. I won't do anything you don't like. As soon as it gets too much, just tell me and I'll stop.” Donnie waited for his little brother to nod again before he leaned in to gently kiss him.

 

He couldn't even express how relieved he was. Mikey had been scared because of something he couldn't help. He thought he was _broken,_ he thought his mates would _abandon_ him because of his mutation. And Donatello couldn't wait to take those fears and doubts away to get his enthusiastic brother back.

 

Moving to sit on the table with Mikey, Donnie deepened the kiss, his hands slowly caressing his sides. Don smiled when he felt the smaller body shudder and broke the kiss to nuzzle the warm neck before letting out a little churr and started nipping the skin there.

 

“You taste so good...” The olive turtle husked before sucking on Mikey's pulse point.

 

Michelangelo's surprised moan encouraged Donnie to leave a mark on the delicious skin, his hands roaming boldly towards the swelling pouch containing Mikey's cock.

 

“D-Donnie... it feels so... so good...” the orange-banded turtle moaned and tilted his head back to make more room for his big brother, who started to kiss his way down to where his hands were coaxing Mikey's shaft out.

 

Donnie was about to reply when a sudden scent hit him. It was the same scent as the night before, triggering some primal instinct deep in him. Swiftly he made Mikey lay down before hovering over him and kissing him possessively. He dropped down and rubbed their cocks together, eliciting churr after churr from his younger brother.

A whimper brought him back to reality. Mikey was squirming around, trying to close his legs, which was impossible with Donnie in between them.

 

“Everything okay? Too much?” he panted out, smoothing a hand over Mikey's head.

 

“No!” the smaller one quickly denied. “I really like it.” That made Donnie smile as he caressed the thighs again. “It's just... it... it starts _leaking_...”

 

Donnie blinked a few times. “Oh. OH.” He leaned down to get another kiss before sitting up on his knees, gently parting the sea-green legs more. “Don't worry, it's okay baby.” he assured before his eyes dropped past the lovely penis towards the tight pink hole. Don bit his lip at the sight and scent. The ring of muscles was darker and swollen, and a clear substance was slowly leaking downward.

Before he knew it a deep churr escaped him.

 

“Tell me, sweetheart... does this feel good?” he husked, voice strained with how much it was taking him to hold back. His finger tentatively brushed over the hot entrance. He was surprised by the violent reaction. Mikey jerked, a loud churr along with a pleasured moan sounding out.

 

“Donnie! What-” he was interrupted by a thick finger breaching him, slowly but steadily. “Oh shell!”

 

The sight of his baby brother panting under him, face flushed and sweaty, writhing with pleasure was too much for the genius. How could he hold back like that? Especially knowing that he was going to be the first one to-

 

“P-Please!” Crashing his lips to Mikey's again, Donnie started to pump his finger into the clenching entrance. With the self-lubrication it was easy to slide in and out, and with how easily Mikey adjusted to the intrusion Donnie knew he enjoyed it. The sea-green hips moved themselves to meet the thrusts, whining when the finger was removed, and churring when it returned along with a second.

 

“Easy sweetheart, I don't want to hurt you.” Mikey bit his lip and closed his eyes. He couldn't believe how utterly _good_ this felt. Especially when Donnie brushed against a bundle of nerves that had him seeing stars. Another jab and before he knew it he came with a shout, painting his own and Donnie's plastron.

The genius gave him a few seconds to recover, kissing and nuzzling his neck, before he moved his fingers again.

 

“Ah...” Mikey whimpered, automatically pushing down to get the digits deeper.

 

“Are you ready for me...?” Donnie asked with a needy strain in his voice. He just couldn't stop now. Not even if he wanted to.

At Mike's nod he removed his fingers, positioning himself. He stopped himself, taking a moment to catch his breath and clear his head. “Y-You sure you want _me_ to do this?”

 

Mikey grabbed his brother's cheeks and pressed their lips together, wrapping his legs around Donnie's hips. At such an invitation Donatello couldn't help but move his hips forward, easing into Mikey's widened channel.

The purple-banded turtle groaned at the hot tightness, despite the prep-work. It just felt perfect.

He gave himself and Mikey a few more seconds to adjust and revel in the intimate feeling. And when he started moving, he felt like he was in heaven. They both did.

 

Donatello was used to submitting to his older brothers, it just felt right to him. But with Mikey, there was this overwhelming need to claim him; to show the dominance he didn't know he had.

 

He felt Mikey growing hard again and reached down to squeeze the shaft, rubbing it to bring him the ultimate pleasure. They moaned simultaneously, moving against each other and kissing and grabbing every inch of the other they could reach. Donnie picked up the pace and force when he felt the knot in his abdomen tighten, letting out a long loud groan when he finally reached his peak, blowing his load into the willing body.

 

Being filled with Donnie's seed brought Mikey right over the edge again, new semen joining the old on their plastrons. The taller turtle collapsed on top of Mikey, holding him close as they came down from their highs.

 

“That... that was amazing...” Michelangelo muttered when his heart calmed down again. Donnie grinned goofily against his brother's plastron before pulling out of him, sitting up. “It was.”

 

When Mikey sat up too, Donnie pulled him into a deep kiss again.

 

“Is... everything okay in there?” Mahagony and sky blue eyes turned to the lab door. Donnie chuckled, still not fully down from his high, as he got up to let his brothers in. Leo and Raph stood on the other side. The leader's eyes were wide when the scent of sex hit him, while Raph looked pervertedly amused.

 

“All good, Leo.” was all Donnie said before settling back on the exam table next to an embarrassed looking Mike. “Don't worry Mikey, they will react pretty much the same as me.” the genius pulled his baby brother close and assured him.

 

“Um... I think I need a few more minutes before I can go again...” Mikey blinked with wide eyes and flushed cheeks, making Donnie laugh and press a kiss to his cheek.

 

“I don't mean the sex part.” he laughed, “Though I'm sure they'd love to get to know your special mutation too.”

 

“Special mutation?” Leo asked from the doorway, a little overwhelmed by the enticing intimate scent of his two youngest brothers. A glimpse towards Raph's buldging lower plastron showed he was equally aroused.

 

Donnie smirked at the sight and shrugged.

 

“Well, yesterday I told you Raph is an alpha turtle. And Mikey... is his counterpart, so to say. He is self-lubricating and highly enjoys being penetrated.” At the last part he let his fingers wander to Mikey's cute little tail, brushing over the still wet entrance on his way there. It made Mikey gasp in pleasure, and suddenly they weren't alone on the exam table anymore...

 

* * *

 


	2. Part 2

**Notes for the Chapter:**

> Okay, this is a requested second part. I hope it turned out okay, since I'm not really good with multi-chapter stuff :)  
> Btw, I want to thank you guys, three of my oneshots are nominated for the TMNT Readers Choice Awards thingy. You are amazing!   
> Enjoy!

* * *

 

 

It was like someone cut a leash; the two older brothers squeezed themselves on the exam table so fast Mikey wasn't sure what was happening. Leo was kneeling between Donnie's legs at the foot end of the bed as he pressed him against the wall, kissing until they both were breathless, fingers roaming all over the olive body underneath. The intense dark blue gaze brought a churr from the genius. He absolutely loved it when Leo let go of his inhibitions.

Grabbing the leaf-green shoulders he pulled him forwards again to resume kissing, moaning when his cock stirred again and was immediately grabbed by Leo's hand.

 

That was the last thing Mikey saw before Raph demanded his full attention. The way the larger turtle was looming over him, pinning him with his electric green gaze only; it made the youngest gulp.

Usually he'd never pass a chance for a stupid joke, especially not at the hothead's expense, but somehow the words got stuck in his throat as he looked up at his older brother. Something was... off. He'd kissed all of his brothers in various ways before, and spent much time in their laps, enjoying the closeness to the fullest.

 

Leo was a careful kisser with him from the very beginning. Starting out slow and always making sure to give Mikey enough time to pull back if he got uncomfortable.

Donnie was a gentle kisser. Just like when he patches them up, his movements are sure and precise. He knew exactly where to touch to drive you crazy.

With Raph, it was all passion. His kisses become quickly demanding, conquering every inch of your mouth. His touches were like fire.

 

Mikey wouldn't mind kissing his big brother like that now. In truth, he had expected the hothead to be all over him already. He wasn't used to this... silent staring. Raph was licking his lips hungrily, shaking as he took deep breaths. Mikey's scent... it stirred something in him. He wanted to, no, he _needed_ to claim him too.

With Donnie and Leo, it happened during their making out. He just took over their first time because it felt right. He'd been lust-filled, yes, but he was in his right mind.

With Mikey... his brain was shutting itself off. The more he took in the scent, the more he felt his instincts take over.

 

Slowly he leaned forward, making Mikey lean backwards and gulp again. Green eyes focused on the sea-green lips in front of him and smirked when Mikey's carapace and head hit the exam table. He placed his hands left and right from the youngest's face and leaned over him, close enough so he could feel his body warmth but not yet touching, lips only an inch from his.

 

“R-Raph...?” Mike asked, nervous that his red-banded brother hasn't even touched him yet while Leo and Donnie were already voicing their pleasure, sounding as if they were already in the middle of fucking.

 

Instead of answering, Raphael finally placed his lips on Mikey's, engulfing him in a passionate kiss before pulling back and churring.

 

“You're going to be mine.” Mikey's eyes widened and a gasp escaped him when Raph latched onto his neck, sucking to leave a large mark right next to Donnie's. Meanwhile one of his hands moved over the smaller body, making sure to not leave an inch untouched. He gradually wandered closer to the twitching entrance that seemed to be calling out to him. A loud pleasured moan echoed when the questing fingers brushed over the swollen muscle and with how easy a finger glided in, Raph figured they wouldn't need much foreplay after all. Mikey was all prepped after having been fucked by Donnie, and his own instincts were screaming at him to just claim him already, so why the shell not?

 

Pressing his lips to his little brother's once again he re-positioned and a second later his cock was pressing in. Raph knew he was larger than Donnie, that's why he was going slower than he wanted to. Mikey seemed to appreciate it at least, and churred into the kiss, wrapping his arms around the strong neck.

 

Raph clenched his teeth at the tight heat squeezing his cock, the small muscle spasms massaging it. It took much effort to not just buck into his younger brother as wildly as his body begged him to. The pleasured sounds coming from Leo and Donnie behind him turned him on even more, the vision of what they were doing at that exact moment eliciting a deep churr and suddenly he couldn't hold back anymore.

Finally acting on his instincts he rapidly moved his hips, desperate to claim the youngest. He pushed in deeper with each thrust, swallowing Mikey's gasps and groans with his own mouth. Raph felt the climax building faster than he had expected and hurried to wrap a hand around his baby brother's cock to bring him off first.

 

Meanwhile Leonardo was buried deep inside Donnie's willing body, the moans turning to soft pleasured cries when the leader brushed against the genius' prostate, hitting it with every teasingly slow thrust.

The midnight blue eyes were fixated on Donatello's flushed face, eyes closed and concentrating on the intense feeling of Leonardo's hot hard flesh inside of him. The katana-wielder wouldn't admit it anytime soon, but he really enjoyed making love like this. It sent shiver after shiver through his body to go slow and revel in the feeling, to watch closely how it brought his smart brother closer and closer to completion until he would reach his breaking point.

He knew from experience that Raph was more fast and way rougher, and he had to admit it was an awesome feeling too, but this, this was Leonardo's heaven.

 

“Aaahng!” Leo shuddered when he felt Don squeeze hard around him as he climaxed. He managed to watch the expression of utter pleasure for another two seconds before he was forced to close his eyes too as his own orgasm hit him. Olive arms wrapped around him as they rode out their last waves of pleasure. He blindly found and kissed those lovely lips lazily before slowly pulling out of the clenching anal passage.

The bed was still rocking, even more noticable now that they were still themselves.

 

“Fuck!” Raph grunted out as he came, squeezing Mikey's cock tight and filling him with his essence. The sperm against his prostate set the orange-banded turtle off too with a rather loud whimper.

The emerald turtle leaned his forehead against the youngest's as they both tried to catch their breaths.

“Fuck...” the hothead repeated, a little quieter this time, “...How can you still be so tight?!”

 

Mikey gave a breathless laugh and closed his eyes, waiting for his heartbeat to finally slow down. “I can't believe we managed to do this on this tiny exam table...” he heard Leo mutter from somewhere behind Raph.

 

“It was definitely not the most comfortable position.” Donnie chuckled as he disentagled himself from Leo and stood to stretch. “We should move the next round to a bedroom...”

 

“Agreed.”

 

Sky blue eyes opened wide before he sat up and blinked at his brothers.

 

“... Next round...?”

 

Raph, who had been forced up too with Mike's motion flicked his beak and smirked.

 

“Of course. We're not done yet. I'm sure Leo wants a turn too...” With an amused expression the hothead turned his head to look at his leader, who eyed Michelangelo hungrily.

 

“You bet I do.” the youngest turtle gulped and sent a pleading look to Donnie, who chuckled and put a hand to Leo's shoulder.

 

“Well, you two came only one time, Mikey and I did two times. I say we watch a movie or something, and then we can go for another round.” He helped Mikey off the bed with a smile and chuckled again when the youngest had problems standing on his own.

 

“Yeah, that sounds totally okay. You can wait for a bit, right Leo?” he asked the oldest. Of course he would give in if Leo really insisted he wanted it right now, because okay, it would be really unfair. But to his great relief Leo chuckled too and nodded as he got up.

 

“Fine, but in return I get to have you two times in a row...” The leader tilted Mikey's head up to kiss him, shortly but intensely.

 

It felt so right. Finally they were able to explore all kinds of things and kinks together, and Leo intended to take advantage of it to the fullest.

 

* * *

 

**Notes for the Chapter:**

> I have another chapter for this, but it's not gonna be smut. I played around a bit with the Mutation idea and well... yeah. You'll see when I post it. See ya around!


	3. Chapter 3

**Notes for the Chapter:**

> For now the last chapter :) at least until Inspiration strikes again...
> 
> Enjoy!

* * *

 

 

_-crash-_

 

Donnie paused in his typing, looking at the ceiling with a suffering sigh before attempting to continue, when another crash sounded along with shouting.

He guessed one of Mikey's pranks got out of hand again, but when there was no younger brother trying to hide in his lab in the next two minutes he began to second guess.

There was the sound of punching and with wide eyes the genius shot up and out towards the sound. The shouting was coming from the dojo; Leo and Raph. Ever since they started to become intimate four months ago their fighting had been lessened and mostly reduced to verbal arguments. To hear them become so violent after so much time was really disconcerting.

 

When Donnie entered the dojo, his older brothers were indeed fighting. What about, he had no idea. But both of them looked rather furious and fought dangerously violent.

 

“Guys! What the shell?!”

 

“None of ya business!” Raph snapped without looking at him, landing a blow to Leo's stomach and earning a punch to the face.

 

Donnie frowned. He had hoped those stubborn idiots finally got over their stupid rivalries. He was tempted to just leave them to it. They would blow off their steam and calm down eventually, and then they could take care of their injuries themselves. See if Donnie cared. But seriously, they were _mates_ for shell's sake! They shouldn't fight like that at all!

 

Making an impulsive decision, he grabbed his Bo staff from the wall and swiftly hit them both on the heads. With them both occupied with punching each other it was an easy feat. They let go of each other in favor of rubbing their heads and turning to their younger brother.

 

“Stay out of this Donatello.” Leo seethed through clenched teeth and if Don was anyone else but himself he would've backed down at the steely glare directed at him.

 

“Not until you tell me what's going on with you!”

 

“I said it's none of ya fucking business!”

 

“It is my business if you almost kill each other! I thought you were over this stupid nonsense fighting!”

 

“Just shut up!” Don actually took a step back at the animalistic glares. Leo's and Raph's eyes were blazing with something close to hatred, directed at each other and himself.

 

“Fine, if you're being assholes you can go fuck yourselves for all I care! No wonder Mikey prefers being with me!”

 

He didn't even know where the last part came from. He was just so freaking mad. And it was true. They've been intimate with each other for a while, and Mikey tended to come to his bed rather than Leo's or Raph's since then. Not necessarily to have sex, but in general.

However, it was the wrong thing to say. His brothers growled and jumped at him and soon they were wrestling on the ground together. Donnie still didn't know what exactly they were fighting about, but he certainly wouldn't let himself be punched to the ground like that.

 

Being on the ground made fighting harder for Don, since it was easier like that for bulky Raph to pin him. Their shouts turned to angry clicks and growls, their animal instincts taking the upper hand. Pushing Leo away, Raph turned Don on his plastron and leaned over him, biting at his neck hard to show his dominance. The genius groaned but also growled then, not wanting to give in so easily. A part of his brain was still working, and it was trying hard to figure out what the actual hell was happening to them. They've had sex quite a few times and it never was so... so animalistic. What triggered it?

 

Leo smashed into their sides, tumbling them over and pinning Raph down. But before he could mark him the bigger turtle threw him off and bit his shoulder. Donnie rubbed the bite mark as he watched his brothers. Using his legs, Leo flipped Raph off hard enough to make him hit the weapon stand. He pounced on Donnie instead. The genius tried to fight him off to gain dominance, but Leo was stronger than him and leaned down to mark the other side of his neck.

 

Since Raph was still working on entangling himself from the weapon stand Leo had time to continue. His hand left one of Donnie's wrists to rub at his lower plastron. His glazed eyes were fixated on Donatello's, the intensity of it enough to make the olive turtle drop down with a churr. The sound was echoed by Leo until an emerald flash pushed him off again. Raph took his place above Donnie before the latter could sit up. He had already dropped down and put his rock hard dripping cock against Don's entrance.

 

The mahagony eyes widened as his mind cleared at that. Raph wouldn't just fuck him dry and without preparation, would he?!

 

“W-Wait! You need to prep me!” The red banded turtle tilted his head and hesitated. Another angry growl and Raph earned a punch to the temple from Leo.

 

Raphael pinned Leo now and attempted to push into him instead. Donnie thought fast and pushed him off of Leo. He needed to stop this before they did some serious damage.

 

He got a few more bruises from the fighting, thinking desperately to of a way to stop this... Until cold water washed over their turtle pile.

 

All three of them blinked and looked up at Master Splinter, who held an empty bucket and seemed... unhappy.

 

“What is going on in here?” he demanded to know now that he had their attention.

 

Leo, Donnie and Raph exchanged confused glances, none of them really knowing how to explain. Gaining back their senses, they tucked themselves away again and blushed.

 

“I don't know, Sensei. I... It just overwhelmed us.” Splinter's eyes narrowed.

 

“You have asked me for my blessing to pursue this relationship and I allowed to to proceed. Now I find you fighting and almost raping each other in the dojo. Was my blessing a mistake, my sons?”

 

His voice was calm, but the words made the turtles' hearts stop.

 

“N-No, of course not!” Raph was the first to find his voice again.

 

“It won't happen again!” Leo seemed just as desperate. He had no idea what happened to them in first place, but he would do anything to be allowed to keep their relationship.

 

Master Splinter turned to look at his smartest son, waiting for an explanation.

 

“I... I don't know what happened, Sensei. But I will find out to make sure it won't happen again.”

 

“Very well. I advise you treat those wounds before dinner.” With that, Splinter turned around and left them to themselves.

 

For a while they just sat there on the ground, looking at each other.

 

“Fuck...” Raph rubbed a hand over his face, wincing when he touched the bruising. “I... I almost raped you...”

 

And yes, Donnie was a little shaken because of that. Because, who wouldn't? Though he wasn't entirely sure if he could blame Raph. It didn't seem like his brothers were in their right mind, and for a while Don wasn't in control either.

 

“It's okay. I guess.” He shook his pounding head. “What _was_ that?” Now that they all were clear in the head he might get a real answer.

 

“I'm not sure. We were sparring. And talking.”

 

“About?”

 

“We were tauntin' each other, as always.”

 

“That never got you that violent before. What did you say?”

 

“I might have bragged about tha alpha turtle thing...” Raph admitted and Donnie felt himself rolling his eyes.

 

“We both know how to push each other's buttons. But I really don't know how it got so bad...” Leo seemed really at loss, so Donnie sighed and nodded.

 

“I think until we figure this out it's better if you don't spar together anymore. Let's get patched up.”

 

They left the dojo, being greeted by a wide-eyed Michelangelo in the living room.

 

“Oh my gosh. What happened?” The worry was oozing off him as he rushed over, gently touching a dark bruise on Leo's temple.

 

“We... uh...” the leader briefly looked over at the other two. “We were sparring.”

 

Mikey blinked. “... Are you serious? This looks really bad.” He winced at the cut on his leader's lip. “And what did Sensei need a bucket of water for?”

 

“Uhm...” All of them averted their gazes. They kinda were glad Mikey wasn't the one finding them, who knew what would've happened if... Suddenly Donnie's eyes widened as his brain caught up.

 

“Oh my god...” he muttered and rubbed his forehead. “I think I know what happened.”

 

Three pairs of eyes were on him, all of them questioning. Donnie sighed and motioned for them to follow him into the lab. There he pulled out the first aid kit and they started to patch each other up.

 

“I think it's because of Mikey.” Donnie started once he was busy. As expected his baby brother recoiled a little.

 

“W-What did I do?”

 

“Absolutely nothing, sweetheart. It's just... Remember what I said about our different mutations?” He pressed a band-aid to a bleeding bruise on Raph's temple. “Like Raph's scent makes us submit to him during love-making.” he explained further. He said love-making, because that in the dojo was nothing like that at all. “And Mikey's scent makes us want to dominate him. Our animal instincts equal him with a female.” He smiled at Mikey's expression. “I _know_ you're not a female, but in nature submissive males are so rare and wild turtles don't really care to separate between the two.”

 

Since none of his brothers said anything he continued.

 

“Could it be you were talking about Mikey when you were sparring?” he directed the question at his older brothers.

 

“We were talkin' bout the two of you. And sex with you.”

 

“And I guess also about fucking Mikey...” Leo said thoughtfully as he crossed his arms. “Then I sort of got mad at Raph and we started the fight I think.” Raphael nodded in confirmation.

 

“When I joined you I said with your attitude it's no wonder Mikey's rather with me. And then you attacked me too. Animals usually fight over the females.” Donnie gave a small laugh. “We fuck each other on daily base and actually started a fight out of jealousy.”

 

“How did this happen? I mean, we have foursomes all the time. We're never jealous.”

 

“I don't really know... maybe because we haven't had sex for a while and our turtle instincts took over...”

 

“If yer sayin' that we should fuck more often I'm totally game.” Raph grinned and Leo actually chuckled.

 

“If we keep it up for longer it could be possible we go into heat. Sensei would be scarred for life and we would be embarrassed till our end.” he laughed again at the thought, but stopped when he saw Mikey's face.

 

“Hey, baby, none of this is your fault.”

 

“You could've seriously hurt each other...”

 

“But we didn't.”

 

“What if it happens again? Donnie, I don't want this... this submissive thing anymore. Isn't there a way to make me normal?”

 

Donatello and the older brothers blinked at Mikey. The genius didn't know how to answer that. His big brain was running over some scenarios already, but it was useless trying to explain.

 

“Baby-” he was interrupted by Leo.

 

“We don't want you to change. You're perfect the way you are.”

 

“Yes, and Donnie said as long as we fuck regularly it's not gonna happen again. So stop this shit.”

 

Mikey sighed and pulled his lips to a pout, while Donnie actually smiled widely before schooling his expression again. It was really nice that someone else took over the assuring.

He pulled his younger brother close and rested his not-injured cheek on his head, while Raph and Leo wrapped themselves around them too.

 

“But I'm not a girl...”

 

The sound of laughter filled the lab, and Mikey couldn't help but join in after a bit of coaxing from his brothers.

Tonight they would take care of the problem and then the tension would finally be gone too.

 

* * *

 


End file.
